Bello, OD;
Jouannot, O;
Chaudhuri, A;
Stroeva, E;
Coleman, J;
Volynski, KE;
Rothman, JE;
(2018)
Synaptotagmin oligomerization is essential for calcium control of regulated exocytosis.
Proceedings of the National Academy of Sciences of the United States of America
, 115
(32)
E7624-E7631.
10.1073/pnas.1808792115.
Preview |
Text
Bello et al_Manuscript_Complete.pdf - Accepted Version Download (1MB) | Preview |
Abstract
Regulated exocytosis, which underlies many intercellular signaling events, is a tightly controlled process often triggered by calcium ion(s) (Ca2+). Despite considerable insight into the central components involved, namely, the core fusion machinery [soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)] and the principal Ca2+ sensor [C2-domain proteins like synaptotagmin (Syt)], the molecular mechanism of Ca2+-dependent release has been unclear. Here, we report that the Ca2+-sensitive oligomers of Syt1, a conserved structural feature among several C2-domain proteins, play a critical role in orchestrating Ca2+-coupled vesicular release. This follows from pHluorin-based imaging of single-vesicle exocytosis in pheochromocytoma (PC12) cells showing that selective disruption of Syt1 oligomerization using a structure-directed mutation (F349A) dramatically increases the normally low levels of constitutive exocytosis to effectively occlude Ca2+-stimulated release. We propose a parsimonious model whereby Ca2+-sensitive oligomers of Syt (or a similar C2-domain protein) assembled at the site of docking physically block spontaneous fusion until disrupted by Ca2+ Our data further suggest Ca2+-coupled vesicular release is triggered by removal of the inhibition, rather than by direct activation of the fusion machinery.
Archive Staff Only
 |
View Item |
